Rectifying tube with glow discharge



Oct. l0, 1933. Q SZ|GET| 1,929,526

RECTIFYING TUBE WITH GLOW DISCHARGE Filed Aug. 25, 1930 GYORGY ZIGETI 14' MQSM Patented'oc'clo, 1933.'Y l 1,929,521;y i

^ uNusD`s-rATES? v 1,929,521; l Y morirme TUBE wrrn ernowV LmsoHAnGE A l eygy sages, Ujpesanar' 'Budapest Hungary, 1 iassigner to Egyesiilt Izzlampa slvillamos` -sgi rszvnytarsasg, Budapest, Hungary 4Application Augustfzs, 1930...seriai No. 417,191, .f *mi in Hungary ,March 18,1930 g 4sentirmi.` `(or. 25e-275) "Ihe invention relates torectifying tubes with ration' of theractive substance coveringithe sur,.-k glow discharge and having several anodes,-and face of the cathode.` Inorder to, remedy this conplate-shaped cathodes of largesuri'ac'e. In such dition, it has beenfproposed to` construct the i tubes it is desirable to use ashigha gas prescathode so that the dischargeacan take; place 5 sure; as possible in order to obtain good etllciency only inthe interior ofthe cathode, i. e.in a 5 and long life. However, the danger of arcing closed space as far/as the discharge isconcerned. back increases with increase inthe gas pressure. In that case the cathode surrounds the work- The greater the pressure 'ofthe filling gas'the ing surface of the anodes, andthe partsof the easier it is for the glow discharge which is pro` anodes which are located outside -thecathodes Y duced in the desired directionto changeV into a must be carefully insulated. Such an arrangef- '65 A, .Y

be independent of the cathode, in which case it ignate similar elements and whereinz. 1

harmful arc dischargebetween anode and" cathment requires avery careful"mounting, and yet ode or between'the anodes. I l a perfect functioningofthe tube isfnotabsolute- In a known arrangement, screens are placed ly guaranteed by it.VV ,n l. V- between the anode and cathode `or betweenthe The present invention vconcernssa Vdischarge 15 anodes to prevent dischargesl in anA undesirable tube which makesuan economic-and-safe opera-l .70'

. direction.'Such an arrangementprevents a distion, without narcing back of theftube,,possible charge from taking place. Such screen may even with 'comparativelyvhigh gas pressures. l also be represented by the cathode itself' which Reference is made hereby to the accompanyingv is constructed correspondingly, but itmay also drawingfwherein similarreferencenumerals.des-1i5 can be' brought to a corresponding potential. Fig. A1 illustrates in perspectivea discharr'ze The discharge between/the anodes may also tube madeaccording'tofthe invention.' be entirely eliminated by the use' of screens. V1ig. 2 illustrates also in perspectives. modifica- However, in that case, as is also known, another tion ofthe tube made according to the invention. harmful phenomenon arises. Thesoecalledyigni- According toll-"lg.`1VV the plate-shapedca'thode 1 80.,-

' tion `voltage for discharges in rareed gases is is placed-between thefanodes 2 and 3 Within the substantially greater than the voltage needed to tubeor bulb 12 having a base 13 provided with the maintain the discharge. Therefore, when a disusual contact prongs 14, 14, the bulb being ihow'- charge between two electrodes has taken place in ever partly broken away to reveal the construe a tube having several electrodes, avdischarge can tion. The cathode supports 15, 15 which inFig. 1 8,5

take place between these and the other elecaredirectly vattached to the cathode V1, and in trodes located in the same space even at a con- Fig. 2 are attached to thelower portion 16 of Y siderably less voltage than the ignition voltage. cathode 8, at least one of the supports lservingY In a. poly-phase rectifier the voltage between the las a conductor for the cathode in known manner.

35 individual anodes is severalk times that of the Both the cathode supports"15,l5 and the anodes 99 voltage existing between the cathode and anode. I 2 and 3 are supported by and project upwardly Thus when a discharge takes place between from the interior electrode support 11. The planeV the anodes, a discharge inthe working direction of the cathode in each caseis perpendicular or between cathode and one anode can take place vat nearly perpendicular to the longitudinal axes of ,40 a much lower voltage than the ignition voltageY the anodes or the supporting tube. Insulating 95 proper. However if a discharge between the tubes'4 and 5 are placed over thejanodes and anodes is prevented by the use of protective leave free only the small parts of the anodes adscreens, the discharge can take place `in the joining the plane of the cathode. In this arrangeworking direction only il?r the voltage between ment' the distribution of the electrical field is cathode and anode attains the value of the ignisuch that "a glowJ discharge may take place be- 190 tion voltage. tween the anodes, butthisglow discharge doesl Therefore, the use of the screens lowers in that not pass into 4an arc discharge even at very high respect the economy of the tube. In another voltages, even wth'a helium fuling of 20-'40 mm. method for the prevention of arcing back, the Hg. pressure. 7

.50 gas pressure is madesosmall that the discharge The effect produced by the arrangement ac- 1195 in the wrong direction which occurs, cannot pass cording to Figure 1 may be still further improved into an arc discharge.y by the arrangement according to Figure 2. In

' However, when thev gas pressure is small a conthis case the cathode is constructed like a box. tinual disappearance of y the filling gas takes The anodes 2 and 3 are surrounded by insulating `455 place, partly in consequence ofthe Vrapid evapo tubes 4 and 5. For the purpose of diminishing 11110 the voltage drop at cathode the surface of the cathode may be coated with an alkaline earth metal or an alkaline earth metal compound. The coating is suitably effected by arranging, for instance, at both sides of the` cathode 8V the channels 6-and 7 in which are placed small rods o r pastilles 9 andlO made out of an alkaline earth metal and protected from harmful atmospheric iniluences by a parain oil coating. After evacuating the tube the cathode 8 is heated in a suitable manner, for example, by means of an elec' tromagnetic eld of high frequency, whereby the alkaline earth metal is evaporated forming a uniform coating on the cathode 8.

Further advantages may be attained if the cathode before it is sealed inthe tube is provided in the manner known with a coating of tungsten bronze or molybdenum bronze. If after evacuation the cathode coated with tungsten bronze or molybdenum bronze is exposed to the vapor of an alkaline earth metal, there appears on the surface of the cathode a very thin layer of material of very low work function which excellently resists the disintegration of the cathode material.

The tubes produced in that manner are suitably lled with helium of 20-40 mm Hg. pressure, but other rare gases of corresponding pressure may also be used.

The evaporation of the alkaline earth metal may also take place after the tube has been filled with gas, in that case the evaporating alkaline earth metal has a strong purifying effect on the gas so that a previous thorough purification of the lling gas becomes superfluous.

Having now particularly described my invention what I desire to protect by Letters Patent of the United States and'what I .claim is:

1. A rectifying glow discharge tube including a cathode having a plurality of plate-shaped members, end pieces between said members providing side openings in said cathode,` said end pieces being provided with receptacles to receivecathode sensitizing material, a plurality of anodes disposed approximately perpendicular to said plate-shaped members and insulating members partially covering said anodes and leaving exposed portions thereof adjacent said side openings in said cathode.

2. A rectifying glow discharge tube including a cathode having a plurality of plate-shaped members, end pieces between said members providing side openings in said cathode, there being channels in said end pieces for receiving cathode sensitizing materials, which channels are disposed parallel to the plate-shaped members of the cathode, a plurality of anodes disposed approximately perpendicular to said plateshaped members and insulating members partially covering said anodes and leaving exposed portions thereof adjacent said side openings in said cathode.

3. A rectifying glow discharge tube containing a cathode provided with a coating of alkaline earth metal and including a plurality of substantially plate-shaped members, converging end pieces disposed upon said members providing side openings in said cathode, which end pieces are providedA with. receptacles adapted to receive cathode sensitizing material, a plurality of anodes disposed approximately perpendicular to said plate-shaped cathode members, insulators partially covering said anodes and exposing portions thereo adjacentto the side openings in the cathode, and a rare gas in said tube at a pressure of about 2O to 40 millimetres of mercury.

4. A rectifying glow discharge tube, including a cathode coated with electronically active material and including a plurality of plane portions disposed opposite to each other, a plurality of partly insulated anodes having exposed portions,

. which cathode is provided with end pieces adapted to receive cathode sensitizing material, and is disposed relatively perpendicular to said anodes and located substantially between the exposed portions of said anodes, and helium gas in said tube having a pressure of about' 20 to 40 millivmetres of mercury.

GYRGY SZIGETI. 

